I was reading Modern Reloading by Richard Lee and he is strongly in favor of crimping pretty much every round, and specifically revolver ammunition. He says the ballistics are better and the cartridge is less likely to fall apart during carry or feeding thru the gun. But most forum posters say not to crimp pistol cartridges.

Why?

He's right.

I just finished putting together some test loads in .45 Colt for use in my new Uburti 1866 "Yellowboy".

Sure to the .454 sizing die and .452 bore and chamber on the rifle it required a good roll crimp (after running the cases half way into a .45acp die as the bullets would fall to far into the case under gravity alone).

Factories crimp ammunition for a reason. I always use a factory crimp die set to at least the amount of crimp on a factory round.

I don't know who "most posters" are (?), but all the revolver handloaders I know use a roll crimp in a bullet cannelure, and either roll or taper crimp a smooth revolver bullet to lightly leave a mark.


I find questions like "but some guy says" rather frustrating. Crimping revolver bullets has been normal for 100+ years.

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Science plus Art

Sorry gents if it's a dumb question, but when I started reloading a year ago I did some googling on crimping and most folks I saw said they never crimp unless it's a magnum load, and the only reason was to prevent the bullet jumping out of the shell. I now see that there are clear advantages to crimping.

So, like I said, why not crimp? Is it harder on the brass?

I always put light crimps on all smaller calibers and/or smaller charged loads and the bigger the charge the heavier I crimp. So 148 wadcutters in 39 spcl. get light crimps and 44 rem mag get heavier crimp. This has always worked well for me. You do not want the recoil of the gun unseating your bullets from the cases. Especially so in revolvers.

A roll crimp in a cannelure is probably harder on the brass than a taper crimp. I say this only because that's where my revolver brass starts cracking. However, I still get several uses out of my brass so to me at least, it's a non issue.

I crimp all handgun loads. Magnums you don’t have any the recoil pushing the bullet into the case and lite loads you want to have positive burn of your powder. On rifle I only crimp auto loader rounds.

Around here it seems pretty much everyone recommends some kind of crimp. I roll crimp all revolver rounds, and the more powder the heavier the crimp.
I use a moderate to heavy taper crimp all bottom feeder rounds.

I roll crimp revolver loads and taper crime semi-auto cartridges. It works for me.

For autos,I taper crimp;technically,I don't really crimp as I only bring the diameter back to its original dimension since most auto rounds will headspace on the mouth of the round.I measure the thickness of the brass X 2 and add the diam of the bullet(for a 9mm shooting .356 lead bullet with .008'' brass that'll be .008X2=.016+.356=.372'' measured at the mouth of the brass).
For revolvers,light load=light roll crimp.Heavy load=heavy crimp.Some powders,even with light loads will burn better(create pressure more evenly)with a heavy crimp.The price to pay is the more you work that brass(more belling coupled with heavy roll crimp)the less reloads you are going to get from it.But hey!I'd rather get 3 or 4 less reloads from the brass but have accurate rounds to shoot from it.

You have a Apples and Oranges post going on.

Yes, revolvers do better with a light or HEAVY crimp depending if..........
you are loading target or heavy SD or Hunting loads.

Why would you crimp a 9mm case when it needs the case to hit the
chamber reamed to have it fit into it for proper headspace?

I know the old Speer # eight had a 124-5 gr JRN that they said to crimp but.......
I would think they wanted a light taper crimp, for that bullet.

Too much crimp on a Pistol load will let it go too far forward to where it
might pass the chamber onto the rifling, to where it is seated too deep
for the firing pin to hit the primer.

Know your limits.......

Another "I crimp" here.

I use a taper crimp on revolver loads with plated bullets. My roll crimp die is set to properly crimp on cannelured bullets and I'm too lazy to change it back and forth. Works for me, but I'm not using stout loads-usually-with plated bullets.

Back in the old days, you frequently saw cannelures on the case at the base of the bullet for semi-auto ammo. This was to help prevent bullet setback during the feed cycle. Then they went to a taper crimp.

There's a school of thought (?) that all you need is neck tension to hold the bullet in place and that crimping was bad for accuracy. I once spent some time at a site called benchrest central and discovered that even the benchresters had started at least slightly crimping their loads. They claimed it produced a more uniform neck tension/bullet pull force and promoted a more consistent powder burn.

So now I am confused? I can not believe that anybody would recommend to not put a crimp whatsoever? When depriming you are also putting a flare or a bell in the mouth of the case. This is to help with seating your projectile after putting in a charge. There is no way to know for sure exactly how much you are flaring it open. This is done by eye and how deep you set your depriming die. Sometimes I will end up with a little less flare and it makes setting the projectile a chore as it wants to sit crooked and shave off material as its pushed in. I have also ended up with cases I flared a little much and in that case it is very easy to seat projectile. So now in scenario #2 that case has very little hold on the projectile. Wouldn't everybody want to put a crimp on the case so the projectile is being held in case with sufficient pressure? I think the notion of not crimping handgun loads is just asking for trouble. I too read Richard Lee modern reloading 2nd edition and his advice on how to set the Lee crimping and then a half to 3/4 turn works perfect for me to set the case back against projectile with a crimp. Many of the Berry's plated bullets I reload do not even have a cannulure on them so putting a light crimp I think is a crucial final step in reloading them!

There can be no doubt that you are correct - this is certainly possible, but it would sure take one heck of a hard crimp.

Just curious whether you have personally ever seen any crimped that far? I'd think that a crimp that extreme would squeeze the bullet diameter down so far that it would almost rattle down the barrel - assuming you got it to fire.

I typically use a light to moderate crimp on revolver loads and a light taper crimp on auto-loader rounds. Most loads don't even need a moderate much less a heavy crimp, but a light crimp keeps everything running smoothly.

I roll crimp ALL handgun loads, and 98% use lead bullets with a crimping groove. When I have more than a few splits in a box, I retire the brass in that box.

I just discarded a box of .45 Colts, and my records indicate they were reloaded 17 times.

Maybe the people that don't crimp are shooting more rifle than handgun. All my handgun rounds go through the Lee FCD and my .223 rounds go through the Lee Collect Crimp Die with a mild crimp.

The reason for the crimp is to prevent the bullet creeping forward in revolvers and to a lesser extent keeping the bullet from getting pushed deeper into the case in semi auto's, but the main reason I use the factory crimp die is because it has a carbide ring that irons out the case and helps to ensure reliable chambering.

A crimp on a rifle bullet is great if it has a "Can"...........

Most of my rifle bullets that I load are "Smooth sided" and do not
need a crimp, except for the 30-06 Remington 150 gr. Core-Lokt
that I use for hunting deer.

Just because a bullet has a "Can" it does not mean that it needs to be crimped.
However it does work for a OAL in the pistol and revolver world
for the correct loading by the bullets maker.

A lot depends on the rifles and pistols magazine's OAL as to what
the maximum OAL of the bullet/case will be per the weapon.
I have a Ruger 22-250 that has a "Large" magazine that lets me
load bullet longer than the manual spec's. with their "Can" measurements.

Not a dumb question at all. Are you sure you didn't read there was no need to crimp RIFLE rounds?

Most, if not all handgun cartridges need some level of crimp. Bullet pull in revolvers and bullet setback in semi-autos is real and can be prevented. In the case of setback pressures can raise so high you can experience a catastrophic failure.

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SWCA #3437

I actually have some handgun ammo that isn't crimped, loaded up right now. It's for a T/C Contender, in .30-30 Winchester. It's a single shot.

Everything else gets crimped.

Basically, the crimp serves two purposes:

1. In semi-auto firearms the crimp helps to prevent bullet set-back during the feeding cycle.

2. In all firearms the crimp helps to prevent bullets backing out of the cases due to recoil of those rounds fired before the cartridge comes into battery.

Additionally, crimping can have an effect on the pressure curve of the cartridge during the discharge cycle. Some calibers, and some powders, do much better when there is consistent and positive resistance provided by the crimp (frequently this is demonstrated with larger charges of slower burning powders).

The primary concern, in my opinion, is to maintain a constant and consistent application so that results do not vary unnecessarily. This requires attention to cartridge trim lengths, seating depths, overall lengths, and precise placement of the crimp (whether roll or taper).

CRIMP period all pistol light / heavy it all depends on caliber pressure and the intended use for said loaded ammo.

I taper crimp my semi-auto pistol loads. For revolver ammo, I use a roll crimp.

Take a close look at factory ammo.
Bring a magnifying glass.... and/or take close ups of them with a smartphone/camera.
Read the vetted manuals we all use.
I was advised to learn to master one caliber at a time.

Stay safe
Have fun
Be a Well Regulated citizen!!!

Note: The interweb has “sailors” stating facts about electricity/electronics that can be as disastrous, if followed, as yelling “fire” in a movie theater with locked doors..... Davy Jones loves company.

I roll crimp all of my revolver rounds, being careful not to get too enthusiastic with the heavier crimping, lest I bulge the case, causing chambering difficulties. I had a conversation with an RCBS tech, and he said that factory crimps are in actuality, overcrimped. (?) Plated bullets, I taper crimp, but I chamfer the case mouth interior to avoid cutting the thin plating.

The RCBS tech recommended what seems to be a very light crimp.

When I started reloading, the small Lyman manual (Number in the single digits) showed illustrations of Light, Medium, and Heavy crimps. I did my best to keep mine mediumish.
Of course to do that, I needed to TRIM the cases...not my favorite activity!

loads for tubular magazines should ALWAYS be crimped, heavy magnum charges of slow burning powder should be crimped firmly. Auto pistol loads should also have adequate taper crimps to prevent bullet setback. …...But working with light target charges in large revolvers you can use much lighter crimps. My .44 target load of 7 grs of Green Dot at 950fps with a 240 gr KSWC requires just the lightest of roll crimps. This is because of the weight of the firearm and the mild charge, I have no issues with bullet pull(629DX), same with target loads in my n frame .41s and K/L frame .357. This includes very mild taper crimp with 10mm in my 610. My point is blanket statements on crimping is a problem. Everyones firearm weights, and loads and even bullet weights will effect the actual need for varing levels of crimp. (light crimp, firm, heavy etc.)

Duuno what dies you use that flare the case mouth on depriming. Most dies combine sizing and depriming and flaring the case mouth is a separate operation, usually in combination with priming or powder charging.

Given that a great many semi-auto pistols effectively headspace on the extractor, the chances of shoving a bullet into the rifling is really, really slim even if you do manage to manage a severe enough crimp to do that.

Finally, just because a bullet doesn't have a cannelure doesn't mean you can't crimp it. I've got a bunch of XM118LR 7.62 that exhibits a very slight crimp on a Sierra Match King right out of the factory.

Degrades accuracy....right....... The crimp is going to put a uniform couple thousandths of an inch depression in a bullet that's going to be crammed into the rifling under thousands of pounds of pressure while the rifling engraves itself. The crimping marks are going to get ironed out by the time the bullet is fully into the rifling. If there was a degradation of accuracy do you think the bench rest crowd would do it?

I slightly roll crimp revolver rounds (even .357) and slightly taper crimp auto rounds.

My personal opinion is that people tend to over-crimp.

The roll crimp on revolvers is to prevent bullets pulling out of the case under recoil. I've had this happen even when shooting light target rounds (158 LSWC + 3.5 gr Bullseye) that I didn't crimp in a 642.

Taper crimp auto cartridges to remove the case flare that was added to aid in seating the bullet. No more than is necessary than to ensure cartridges feed freely. Taper crimp does not prevent bullet setback - neck tension does. Crimping reduces neck tension, so keep it at a minimum.

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Common sense isn't so common.

Older RCBS dies and possibly other brands deprime with the flaring/expander die. I think it changed about 40 years ago to the sizing die.

I have the factory crimp dies, but I have my dies set up, so they crimp when seating the bullet..... since you have to seat the bullet, why not crimp at the same time ?

On a pistol cartridge, even with an excessive crimp, the pistol's extractor would limit how far the cartridge would enter the chamber and likely it would not allow it to exceed the firing pin's travel.

Seating and crimping separately can improve accuracy. When doing both in one step, the bullet is still moving as the crimp is applied. This can deform the bullet.

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Common sense isn't so common.

Do you chrono your uncrimped 30-30s and have you compared accuracy/velocity with a slight taper crimp?
I have tried that with my #1 in 458WinMag but didn’t have a chrono in my youth and the accuracy was the same.
Some of the 45ACP bullseye shooters have strong opinions on degree of taper crimping.
Always wanted a Contender or an XP100.
If I can still see when the grandkids want to take Elk from the field rather than the butcher shop.... I’d like one of each to give to them..... 460 S&W Mag and 223 Rem twisted for heavy bullets.

Reloading: the science and art outlined in the 2nd.

I've been reloading for 50 years and never saw that. Interesting though.

You can absolutely do it this way. I prefer a separate step. I use the Lee Carbide crimp die. The crimp is really easy to duplicate.
The die has a knob on top that you can mark . 1/4 turn for light crimp. 1 full turn for a heavy crimp or anything in between.
I load 45 acp with a taper crimp for both auto and revolvers.
I don’t crimp anything for rifles. Friction fit only.

My 38 special dies deprime and expand. The date on the sizing die is 74. It’s an old set that you have to lube the cases. I’ve bought a Carbide sizer but still use the expander and seater.

Looking at the date on that die reminded me of starting reloading. I started in 1965 loading for 357 and 38 special. But a friend and I shared dies. Bought my own about 10 years later.